feat: initialize thirst on NPC spawn, handle old saves missing thirst

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/game/spawner.ts

@@ -15,6 +15,7 @@ export function spawnNPC(world: World, map: GameMap, positionHint?: Position, ev
   world.addComponent<Position>(entity, 'position', pos);
   world.addComponent<Needs>(entity, 'needs', {
     hunger: 40 + Math.random() * 40, // 40-80
+    thirst: 40 + Math.random() * 40, // 40-80
     energy: 40 + Math.random() * 40,
     productivity: 60 + Math.random() * 40, // 60-100
   });

server/src/persistence/entitySerializer.ts

@@ -109,6 +109,11 @@ function deserializeComponent(name: string, json: string): unknown {
       }
       return parsed;
     }
+    case 'needs': {
+      const needs = parsed as any;
+      if (needs.thirst === undefined) needs.thirst = 80;
+      return needs;
+    }
     case 'name':
       // These are strings directly
       return parsed;